A car like that can't go unnoticed especially without plates and the noise. It would be stopping for fuel very often due to size of tank and setup of the car and I imagine it would be a ***** to drive on the road.
Thing is, the car can't be sold and the parts are pretty unique and very top end. As above, it must have Bren stolen to order because nobody is stupid enough to try selling parts like that if they're smart enough to steal it...